1. Field of the Invention
The present invention relates generally to nanocomposites of polymers with dispersed nanotubes and methods of making them. More specifically, the present invention relates to the dispersal of single walled nanotubes (SWNTs) into polyethers, such as polyethylene oxide (PEO) and its low molecular weight analog polyethylene glycol (PEG), still more particularly with geometrical percolation at about 0.09 wt. % SWNT and an electrical percolation at about 0.03 wt. % SWNT at room temperature.
2. Description of the Background Art
Carbon nanotubes (CNTs), including multiple concentric shells and termed multi-walled carbon nanotubes (MWNTs), were discovered by Iijima in 1991 (Iijima, Nature, 1991, 354, 56). Subsequent to this discovery, single-walled carbon nanotubes (SWNTs), including a single graphene rolled up on itself, were synthesized in an arc-discharge process using carbon electrodes doped with transition metals (Iijima et al., Nature, 1993, 363, 603; and Bethune et al., Nature, 1993, 363, 605).
The extraordinary mechanical, electrical and thermal properties of nanotubes make them outstanding materials to blend with polymers to prepare potentially multifunctional nanocomposites. However, development of polymer nanocomposites with dispersed carbon nanotubes has tended to be stymied by the lack of dispersion of the nanotubes, due to their strong inter-tube interactions.
Thus, investigations of polymer nanocomposites with dispersed carbon nanotubes and methods of preparing them have been ongoing. Because nanotubes are largely chemically inert, it has not been expected that chemical methods of dispersion would be successful. Successful methods of dispersion have tended to involve mechanical agitation. Reports of investigations include: F. Du, et al., J. Polymer Sci. B 41, 3333-3338 (2003); H. J. Barraza, et al. Nanoletters 2, 797-802 (2002); K. D. Ausman, et al. J. Phys. Chem. 104, 8911-8915 (200); and O. Probst, et al. Polymer 45, 4437-4443 (2004).
Notwithstanding the above teachings, there remains a need for composites of polymers with dispersed nanotubes exhibiting desirable properties and method of making the composites.